1. Field of the Invention
The present invention generally relates to heat engines and, more particularly, to a simplified Stirling cycle type engine in which heat from an external source is converted to useful mechanical energy.
2. Description of the Prior Art
A Stirling cycle machine is a device which operates on a regenerative thermodynamic cycle, with cyclic compression and expansion of the working fluid at different temperature levels, and where the flow is controlled by volume changes, so that there is a net conversion of heat to work or vice versa. In a typical Stirling cycle engine, operating as a prime mover, heat is supplied to the working fluid at some high temperature T.sub.max, when the fluid is in a hot chamber. Part of the heat is converted to work when the working fluid, due to the absorbed heat, expands and thereby pushes on a piston, which is coupled to a crankshaft and imparts rotary motion thereto. The working fluid is then displaced by a displacer through a regenerator and forced into a cold chamber, which is at some lower temperature, T.sub.min. As the working fluid passes through the regenerator the latter absorbs some of the heat of the passing working fluid. The working fluid is then compressed and some of its heat is rejected and absorbed by air or water used to maintain the cold chamber at T.sub.min. Thereafter, the working fluid is forced out of the cold chamber by the displacer through the regenerator into the hot chamber, and as it passes the regenerator it reabsorbs some of the heat previously deposited thereat. In the hot chamber it again absorbs heat and the cycle of operation repeats itself.
In the Stirling cycle engine operating as the prime mover, the working fluid expansion takes place in the hot chamber, while most of the compression takes place in the cold chamber. As is appreciated by those familiar with the art when the Stirling cycle is used in a refrigerating machine the working fluid expansion occurs in the cold chamber while the compression of the working fluid, during which heat is rejected, takes place in the hot chamber. In either type machine the working fluid is shifted between the two chambers through a regenerator by means of the displacer. The motion of the latter is generally synchronized with the piston motion by means of mechanical linkages which adds to the complexity of the machine.